1. Field of the Invention
This invention generally relates to occupant safety during a collision, and more specifically to an energy absorber that absorbs energy imparted by an incident object that impacts the absorber, and a method for configuring the absorber.
2. Background Art
There have been proposed various ways to protect the occupant or rider of an automobile when the occupant impacts the A and B pillars, headliner, or any hard structure during an impact. Illustrative approaches are described in commonly owned U.S. Pat. Nos. 6,247,745 and 6,199,942; and U.S. Pat. No. 6,443,513, which issued on Sep. 3, 2002 to Glance.
It is known, for example, to deploy truncated plastic cones at rollover stiff points or on door panels for side impacts with the objective of providing better performance than energy absorbent foam. Also, such cones may be less expensive to manufacture. Manufacturing economics have been realized from the raw materials being melt recyclable. Such structures not only provide weight savings and a better performance, but also a cost advantage which may amount to $4-$5 per vehicle.
The required energy absorption characteristics are defined in Federal Motor Vehicle Standards 201. To meet the relevant standards, the industry continues its quest not only for the physical structures that conform to federally mandated standards, but also to develop computer modeling protocols that predict head injury sustained from impacting forces and comparing the results with head injury criteria. It would be desirable in such developments to measure actual head impact (of, for example, a dummy occupant) during in-vehicle testing at selected locations in the vehicle. Ideally, the actual measurements will approximate the values predicted by computer dynamic finite element analysis.
Additionally, the desire to reduce costs while complying with End of Life Vehicle (ELV) legislation in Europe stimulates the use of mono-materials in automotive interior soft trim applications. Related considerations emphasize recyclability of automotive plastics. The impact or influence of the ELV directive on automotive interiors will be felt in various ways: e.g., cost effective use of recycling techniques with environmentally benign consequences. Most interior modules today are made from a combination of skin/foam/substrate. Thus, the materials currently used may present challenges to the recycling task. Such challenges may be met by more use of energy absorbing modules that are made from mono-materials. Such materials might, for example, include polyolefins and melt recyclable polymers, since they show promise as being versatile alternatives to skin/foam/substrate.
It is expected that Europe will adopt the U.S. HIC(d) requirements. This will affect the choice and quantity of materials used for energy absorbers in headliners. Similar door trim panel requirements apply to the pelvis and torso (side impact applications). It is therefore anticipated that there will be an increase in the usage of energy absorbers that will be incorporated into the structure of modules such as door trim panel, instrument panel uppers, and headliners.
To meet cost reduction goals, there is an increasing desire to manufacture interior modules using a reduced number of manufacturing steps.
In light of these and related approaches, there remains the desire to absorb as much impact energy in as little crush distance as possible, with as little weight as possible, yet be capable of being designed and manufactured under favorable economic conditions.